Rotary machine with axial stop incorporating a current generator

Abstract

The rotary machine comprises a rotary shaft (2) supported by first and second radial magnetic bearings (5, 6) that are electrically controlled by a control device (13), said rotary shaft being fitted with an axial abutment device (100) comprising a rotor formed by a disk (101) secured to the rotary shaft (2) and interposed between first and second stators (102, 104) formed annularly around the rotary shaft and each including at least one annular coil (103; 105) controlled electrically by a system for servo-controlling the axial position of the rotary shaft. The stator (104) of the axial abutment device (100) further comprises a secondary induction circuit (106), and the disk (101) secured to the rotary shaft comprises a primary induction circuit (107) so that during rotation of the shaft, electricity is excited in the secondary induction circuit in order to supply energy to the radial magnetic bearings.

Description

[0001]The present invention relates to a rotary machine, for example a turbopump, comprising a rotary shaft supported by radial active magnetic bearings. More particularly, the invention relates to an emergency supply of electricity to radial and axial magnetic bearings, in particular for devices that are designed to operate in explosive atmospheres.PRIOR ART[0002]The use of rotary machines having magnetic bearings is becoming more and more widespread. The active magnetic bearings used in machines of this type use electromagnet devices which are operated by electricity and therefore require an electrical power supply.[0003]FIG. 7 shows an example of a turboexpander. The machine comprises a rotary shaft 2 which is surrounded by two radial magnetic bearings 5 and 6 placed in the vicinity of the two ends of the shaft, together with a double-acting axial abutment. First and second wheels 3 and 4 are fixed to respective ends of the shaft 2. The first wheel 3 is situated on the left of th...

AI Technical Summary

Benefits of technology

"The present invention provides a rotary machine with an emergency power supply that is compact and can control the magnetic bearings even when the machine does not have an internal electric motor. The machine includes a rotary shaft, first and second radial magnetic bearings, and an axial abutment device with a rotor and stators. The stator of the axial abutment device has a secondary induction circuit to produce electricity to power the magnetic bearings during rotation of the shaft. The permanent magnets in the disk on the rotary shaft are arranged in two series on different circles of diameter to form a housing for the secondary induction circuit. The secondary induction circuit may include a toroidal winding or a printed circuit with a plane winding. The control device for the radial magnetic bearings is connected to the secondary induction circuit to receive the electricity generator. The control device may be fixed on the machine and include an explosion-proof covering."

Problems solved by technology

However, the rotary shaft is allowed to land on the auxiliary bearings only below a certain speed which is slow enough to avoid any risk of damaging or destroying the shafts and the bearings.

For reasons of cost and equipment mobility, it is not always possible for control cabinets to be located remotely in protected environments.

Since it is not possible to totally deactivate batteries, which is essential for equipment in explosive zones, the batteries must be located outside the dangerous environment.

Consequently, such a configuration for the system comprising the system and its power supplies does not make it possible to have a system that is completely independent in explosive atmosphere zones.

Furthermore, since the lifetime of batteries is limited and since they are awkward to maintain, it is always advantageous to be able to avoid using batteries in machines of that type.

Nevertheless, that solution can be envisaged only for motor-driven rotary machines, whereas there are now many small turbomachines having magnetic bearings for which considerations of cost and bulk do not make it possible to include a conventional alternator which would alter the performance of such a machine of small dimensions.

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